Farm Fencing
Field Fence Buying Guide: Hinge Joint vs. Fixed Knot
Field fence is one of the few products where the cheapest option is usually the most expensive over its life. This guide works through the decisions that actually determine whether a fence lasts ten years or forty.
Start with the animals, not the price list
The controlling question is what the fence has to contain, and how hard those animals will push against it. A boundary that carries sheep and a boundary that carries deer under pressure are different engineering problems, even if the fence looks similar in a photograph.
Three inputs normally settle the specification: the smallest animal to be retained, the largest animal that will lean on the fence, and whether the fence protects breeding stock from outside animals or simply marks a boundary.
Hinge joint or fixed knot
In a hinge joint fence, the vertical stay wraps around the horizontal line wires. The crossing points can move slightly, so the fence flexes and recovers when an animal pushes it or when the ground moves. This is what allows the roll to follow undulating terrain without being strained.
In a fixed knot fence, the stay is locked to the line wire at every crossing. The fence becomes far more rigid, resists sustained pressure better, and holds its tension on long straight runs. The trade-off is stiffness: it does not accommodate uneven ground as gracefully, and it costs more per metre.
A practical rule is that hinge joint suits sheep, cattle and general mixed grazing, while fixed knot is chosen where deer, heavy pressure or long service life on open ground make rigidity worth paying for.
Wire count, height and stay spacing
The graduated pattern — small openings near the ground, larger ones towards the top — is what allows one fence to retain both lambs and cattle. Removing that graduation to save wire is one of the most common specification mistakes.
| Stock | Typical height | Line wires | Stay spacing |
|---|---|---|---|
| Sheep and lambs | 900 – 1,000 mm | 7 – 9 | 150 – 200 mm, small openings at the bottom |
| Cattle | 1,000 – 1,200 mm | 8 – 11 | 200 – 300 mm |
| Horses | 1,200 – 1,500 mm | 9 – 12 | closer stays with a visible rigid top |
| Deer and wildlife | 1,800 – 2,400 mm | 12 – 13 | fixed knot, tight spacing |
Galvanizing: the decision that sets service life
Field fence rarely fails because the wire breaks. It fails because the zinc coating is consumed and the wire then rusts through. Coating class therefore dominates service life more than any other single choice.
Standard class coating is adequate for dry inland conditions and moderate expectations. Heavy class coating, roughly three times the zinc mass, is the right choice where the fence must last decades, where the site is coastal or humid, or where the fence line is difficult and expensive to re-reach.
It is worth calculating that trade-off explicitly. If re-fencing a remote paddock costs more in labour and machinery than the difference in wire price, the heavier coating is the cheaper option over the life of the fence.
Installation details that decide whether the fence performs
- ›Corner, end and gate assemblies carry the strain of the whole run and need their own bracing. A well-specified roll strained against a weak end assembly will still fail.
- ›Strain the wire evenly. Over-tensioning shortens the life of both the wire and the posts; under-tensioning lets animals push through the gaps.
- ›Follow the ground contour rather than forcing the fence to run straight across dips. The hinge joint exists for this purpose.
- ›Keep the bottom wire close to the ground where small animals are involved, and check that it stays there after the first wet season.
- ›Use compatible metals at every fixing point. Dissimilar metals in contact will corrode one of the two components.
What to put in the enquiry
A useful enquiry states the animals, the total fence length, the terrain, the expected service life and the coating class wanted. It also helps to say whether the site is coastal, because that single fact often changes the recommended coating more than anything else.
Where the budget is tight, it is usually better to reduce the fence height or the wire count than to reduce the coating class. The first two are visible and can be changed later; the third cannot.
Key points
- ›Choose the coating class first — it decides service life more than any other option.
- ›Hinge joint flexes and follows terrain; fixed knot is rigid and resists sustained pressure.
- ›Keep the graduated mesh pattern; it is what allows one fence to retain both small and large stock.
- ›Corner and end bracing is as important as the roll specification.
- ›If the budget must be cut, cut height or wire count, not the galvanizing.